This week, the little boy filmed in front of a green screen and shot scenes with Chicago Mayor Rahm Emanuel and the Chicago Bulls’ mascot Benny. About 100 volunteers showed up to be extras in the film and pretended like they were running away from the giant lizard.

"His parents have been talking about the joy that they’re seeing in their kid again, like, ‘Oh, there’s my boy again. There’s the joy that I remember in my little guy Maddex,’" Stephanie Springs, the CEO of Make-A-Wish Illinois, told ABC News.

"Madzilla" will make its debut next month and will include a 3-minute extended trailer of the movie, plus a 15-minute documentary chronicling Maddex’s Make-A-Wish experience.

"This experience is shaping this 5-year-old boy in so many ways and who knows what we’ll see 10, 15, 20 years down the road when we touch base with Maddex," Springs told ABC News. "Right now we know it’s going to help him pull through the rest of his treatments."